U.S. patent number 5,954,097 [Application Number 08/696,712] was granted by the patent office on 1999-09-21 for papermaking fabric having bilaterally alternating tie yarns.
This patent grant is currently assigned to The Procter & Gamble Company. Invention is credited to Glenn David Boutilier.
United States Patent |
5,954,097 |
Boutilier |
September 21, 1999 |
**Please see images for:
( Certificate of Correction ) ** |
Papermaking fabric having bilaterally alternating tie yarns
Abstract
A papermaking belt comprising a top (web facing) layer of
interwoven top layer yarns, a bottom (machine facing) layer of
interwoven bottom layer yarns, and a plurality of tie yarns. The
top layer yarns comprise a plurality of top layer carrier yarns
interwoven in a weave with a plurality of top layer cross-carrier
yarns, the top layer carrier yarns being perpendicular to the top
layer cross-carrier yarns. The bottom layer yarns comprise a
plurality of bottom layer carrier yarns interwoven in a weave with
a plurality of bottom layer cross-carrier yarns, the bottom layer
carrier yarns being perpendicular to the bottom layer cross-carrier
yarns. The top layer and the bottom layer are tied together in a
parallel and interfacing relationship by a plurality of tie yarns
having a general direction of the top layer carrier yarns and
passing over the top layer cross-carrier yarns and under the bottom
layer cross-carrier yarns in a repeating pattern. As each of the
tie yarns passes over at least one of the top layer cross-carrier
yarns and under at least one of the bottom layer cross-carrier
yarns, each of the tie yarns bilaterally alternates about one top
layer carrier yarn in the direction of the top layer cross-carrier
yarns whereby forming an undulating line passing at spaced
intervals completely underneath that top layer carrier yarn about
which each of the tie yarns alternates.
Inventors: |
Boutilier; Glenn David
(Cincinnati, OH) |
Assignee: |
The Procter & Gamble
Company (Cincinnati, OH)
|
Family
ID: |
24798236 |
Appl.
No.: |
08/696,712 |
Filed: |
August 14, 1996 |
Current U.S.
Class: |
139/383A;
428/131; 428/137; 428/135 |
Current CPC
Class: |
D21F
1/0036 (20130101); D21F 1/0045 (20130101); Y10T
428/24322 (20150115); Y10T 428/24306 (20150115); Y10T
428/24273 (20150115) |
Current International
Class: |
D21F
1/00 (20060101); D03D 003/00 () |
Field of
Search: |
;428/131,247,257
;139/383A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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279 214 |
|
Aug 1988 |
|
DE |
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WO 91/14813 |
|
Oct 1991 |
|
WO |
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WO 93/10304 |
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May 1993 |
|
WO |
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Primary Examiner: Falik; Andy
Attorney, Agent or Firm: Vitenberg; Vladimir Huston; Larry
L. Linman; E. Kelly
Claims
What is claimed is:
1. A papermaking belt comprising:
a top layer of interwoven top layer yarns, said top layer yarns
comprising a plurality of top layer carrier yarns interwoven in a
weave with a plurality of top layer cross-carrier yarns, said top
layer carrier yarns being substantially perpendicular to said top
layer cross-carrier yarns;
a bottom layer of interwoven bottom layer yarns, said bottom layer
yarns comprising a plurality of bottom layer carrier yarns
interwoven in a weave with a plurality of bottom layer
cross-carrier yarns, said bottom layer carrier yarns being
substantially perpendicular to said bottom layer cross-carrier
yarns;
said top layer and said bottom layer being tied together in a
substantially parallel and interfacing relationship by a plurality
of tie yarns having a general direction substantially parallel to
said top layer carrier yarns and said bottom layer carrier yarns,
said tie yarns passing over said top layer cross-carrier yarns and
under said bottom layer cross-carrier yarns at spaced intervals in
a repeating pattern such that as each of said tie yarns passes over
at least one of said top layer cross-carrier yarns and under at
least one of said bottom layer cross-carrier yarns, each of said
tie yarns bilaterally alternating about at least one of said top
layer carrier yarns or at least one of said bottom layer carrier
yarns in the direction of said cross-carrier yarns whereby said
each of said tie yarns forms an undulating line passing completely
underneath said at least one of said top layer carrier yarns or
completely over said at least one of said bottom carrier yarns at
spaced intervals intermediate two adjacent maxima of bilateral
alternation of said tie yarn.
2. A belt according to claim 1, wherein said general direction of
said plurality of tie yarns is substantially parallel to a machine
direction.
3. A belt according to claim 2, wherein the cross-sectional area of
said tie yarns is less than the cross-sectional area of said top
layer yarns.
4. A belt according to claim 3, wherein the cross-sectional area of
said tie yarns is less than the cross-sectional area of said bottom
layer yarns.
5. A belt according to claim 2, wherein said plurality of tie yarns
comprises adjunct tie yarns.
6. A belt according to claim 2, wherein said plurality of tie yarns
comprises integral tie yarns.
7. A belt according to claim 6, wherein said plurality of tie yarns
comprises said bottom layer yarns.
8. A belt according to claim 7, wherein said plurality of tie yarns
further comprises said top layer yarns.
9. A belt according to claim 6, wherein said plurality of tie yarns
comprises said top layer yarns.
10. A belt according to claim 1, wherein said general direction of
said plurality of tie yarns is substantially parallel to a
cross-machine direction.
11. A belt according to claim 10, wherein said plurality of tie
yarns comprises adjunct tie yarns.
12. A belt according to claim 10, wherein said plurality of tie
yarns comprises integral tie yarns.
13. A belt according to claim 12, wherein said plurality of tie
yarns comprises said bottom layer yarns.
14. A belt according to claim 13, wherein said plurality of tie
yarns further comprises said top layer yarns.
15. A belt according to claim 12, wherein said plurality of tie
yarns comprise said top layer yarns.
16. A papermaking belt according to claim 1, further comprising a
framework joined to said belt and extending outwardly from a
web-facing side of said top layer to form a web-contacting
surface.
17. papermaking belt comprising:
a top layer of interwoven top layer yarns, said top layer yarns
comprising a plurality of machine direction top layer yarns
interwoven in a weave with a plurality of cross-machine direction
top layer yarns, said cross-machine direction top layer yarns being
substantially perpendicular to said machine direction top layer
yarns;
a bottom layer of interwoven bottom layer yarns, said bottom layer
yarns comprising a plurality of machine direction bottom layer
yarns interwoven in a weave with a plurality of cross-machine
direction bottom layer yarns, said cross-machine direction bottom
layer yarns being substantially perpendicular to said machine
direction bottom layer yarns;
said top layer and said bottom layer being tied together in a
substantially parallel and interfacing relationship by a plurality
of machine direction tie yarns passing over said cross-machine
direction top layer yarns and under said cross-machine direction
bottom layer yarns at spaced intervals in a repeating pattern such
that as each of said machine direction tie yarns passes over at
least one of said cross-machine direction top layer yarns and under
at least one of said cross-machine direction bottom layer yarns,
said each of said machine direction tie yarns bilaterally
alternates about at least one of said machine direction top layer
yarns and at least one of said machine direction bottom layer yarns
in the cross-machine direction, whereby said each of said machine
direction tie yarns forms an undulating line passing completely
underneath said at least one of said machine direction top layer
yarns at spaced intervals intermediate two adjacent maxima of
bilateral alternation of said each of said machine direction tie
yarns.
18. A papermaking belt comprising:
a top layer of interwoven top layer yarns, said top layer yarns
comprising a plurality of machine direction top layer yarns
interwoven in a weave with a plurality of cross-machine direction
top layer yarns, said cross-machine direction top layer yarns being
substantially perpendicular to said machine direction top layer
yarns;
a bottom layer of interwoven bottom layer yarns, said bottom layer
yarns comprising a plurality of machine direction tie yarns
interwoven in a weave with a plurality of cross-machine direction
bottom layer yarns, said cross-machine direction bottom layer yarns
being substantially perpendicular to said machine direction tie
yarns;
said top layer and said bottom layer being tied together in a
substantially parallel and interfacing relationship by said
plurality of machine direction tie yarns passing over said
cross-machine direction top layer yarns at spaced intervals in a
repeating pattern such that as each of said machine direction tie
yarns passes over at least one of said cross-machine direction top
layer yarns, said each of said machine direction tie yarns
bilaterally alternates about a corresponding machine direction top
layer yarn in the cross-machine direction, whereby said each of
said machine direction tie yarns forms an undulating line passing
completely underneath said corresponding machine direction top
layer yarn at spaced intervals intermediate two adjacent maxima of
bilateral alternation of said each of said machine direction tie
yarns.
19. A papermaking belt according to claim 16, further comprising a
framework joined to said belt and extending outwardly from a
web-facing side of said top layer to form a web-contacting
surface.
20. A papermaking belt comprising:
a top layer of interwoven top layer yarns, said top layer yarns
comprising a plurality of machine direction top layer yarns
interwoven in a weave with a plurality of cross-machine direction
top layer yarns, said cross-machine direction top layer yarns being
substantially perpendicular to said machine direction top layer
yarns;
a bottom layer of interwoven bottom layer yarns, said bottom layer
yarns comprising a plurality of machine direction bottom layer
yarns interwoven in a weave with a plurality of cross-machine
direction bottom layer yarns, said cross-machine direction bottom
layer yarns being substantially perpendicular to said machine
direction top layer yarns,
said plurality of machine direction top layer yarns and said
plurality of machine direction bottom layer yarns comprising a
plurality of machine direction top/bottom-integral tie yarns;
said top layer and said bottom layer being tied together in a
substantially parallel and interfacing relationship by said
plurality of machine direction top/bottom-integral tie yarns
passing over said top layer yarns and under said bottom layer yarns
at spaced intervals in a repeating pattern such that as each of
said plurality of machine direction top/bottom-integral tie yarns
passes over at least one of said cross-machine direction top layer
yarns or under at least one of said cross-machine direction bottom
layer yarns, each of said machine direction top/bottom-integral tie
yarns bilaterally alternates in the cross-machine direction about a
corresponding machine direction top layer yarn or about a
corresponding machine direction bottom layer yarn, whereby each of
said machine direction top/bottom-integral tie yarns forms an
undulating line passing completely underneath said corresponding
machine direction top layer yarn or completely over said
corresponding machine direction bottom layer yarn at spaced
intervals intermediate two adjacent maxima of bilateral alternation
of said each of said machine direction tie/bottom-integral tie
yarns.
Description
FIELD OF THE INVENTION
The present invention is related to papermaking bets useful in
papermaking machines for making strong, soft, absorbent paper
products. More particularly, this invention is concerned with
papermaking fabrics, or belts, comprised of two layers.
BACKGROUND OF THE INVENTION
Paper products are used for a variety of purposes. Paper towels,
facial tissues, toilet tissues, and the like are in constant use in
modern industrialized societies. The large demand for such paper
products has created a demand for improved versions of the
products.
Generally, the papermaking process includes several steps. An
aqueous dispersion of the papermaking fibers is formed into an
embryonic web on a foraminous member, such as Fourdrinier wire, or
a twin wire paper machine, where initial dewatering and fiber
rearrangement occurs.
In a through-air-drying process, after the initial dewatering, the
embryonic web is transported to a through-air-drying belt
comprising an air pervious deflection member. The deflection member
may comprise a patterned resinous framework having a plurality of
deflection conduits through which air may flow under a differential
pressure. The resinous framework is joined to and extends outwardly
from a woven reinforcing structure. The papermaking fibers in the
embryonic web are deflected into the deflection conduits, and water
is removed through the deflection conduits to form an intermediate
web. The intermediate web is then dried at the final drying stage,
similarly to the conventional papermaking described above. At the
final drying stage, the portion of the web registered with the
resinous framework may be subjected to imprinting--to form a
multi-region structure.
Through-air-drying paper webs are made as described in commonly
assigned U.S. Pat. No. 4,514,345 issued to Johnson et al. on Apr.
30, 1985; U.S. Pat. No. 4,528,239 issued to Trokhan on Jul. 9,
1985; U.S. Pat. No. 4,529,480 issued to Trokhan on Jul. 16, 1985;
U.S. Pat. No. 4,637,859 issued to Trokhan on Jan. 20, 1987; U.S.
Pat. No. 5,334,289 issued to Trokhan et al on Aug. 2, 1994. The
foregoing patents are incorporated herein by reference for the
purpose of showing preferred constructions of patterned resinous
framework and reinforcing structure type through-air-drying belts.
Such belts have been used to produce commercially successful
products such as Bounty paper towels and Charmin Ultra toilet
tissue, both produced and sold by the instant assignee.
The woven reinforcing structure of the through-air-drying belts
stabilizes and strengthens the resinous framework and reduces the
permeability of the papermaking belt. Therefore, the reinforcing
structure must have a suitable projected open area in order to
allow the vacuum dewatering machinery employed in the papermaking
process to adequately perform its function of removing water from
the intermediate web, and to permit water removed from the web to
pass through the papermaking belt. Therefore, the reinforcing
structure should be highly permeable to fluids such as air and
water.
At the same time, the reinforcing structure also serves an
important function of supporting the cellulosic fibers, not
allowing them be completely separated from each other or to be
blown through the papermaking belt as a result of application of a
vacuum pressure. These phenomena cause pin-sized holes, or
pinholes, in the paper web. A large amount of pinholes reduces the
quality of the paper web and may negatively affect the consumers'
perception of the paper product. Therefore, the amount of fiber
support provided by the reinforcing structure is of primary
importance. Generally, a trade-off exists between the air
permeability and fiber support of a papermaking belt. This
trade-off is especially sensitive in through-air-drying belts which
must have adequate open area for removing water from the web
through the papermaking belt. Improvement in the fiber support of a
belt by reducing its projected open area reduces the air
permeability of the belt, or, vice versa, improvement in the air
permeability of the belt by increasing its projected open area
reduces the fiber support of the belt.
In order to mitigate the negative consequences of this trade-off
between the air permeability and the fiber support of a papermaking
belt, the early through-air-drying belts comprised a fine mesh
reinforcing element. While such a fine mesh provided an acceptable
fiber support, it was generally impractical because it did not
provide necessary seam strength and resistance to the high
temperatures encountered in papermaking.
A new generation of through-air-drying papermaking belts addressed
these concerns. In these belts, a dual layer reinforcing structure
significantly improved the seam strength and durability of the
belts. In some dual layer reinforcing structures, a single
cross-machine direction yarn system ties two machine direction yarn
layers together, with the result of having vertically stacked
machine direction yarns.
The use of a triple layer belt further improves a fiber support of
the reinforcing structure. A triple layer belt comprises two
completely independent woven layers, a top layer and a bottom
layer, each having its own machine direction yarns interwoven with
its own cross-machine direction yarns. The two independent woven
elements are tied together with tie yarns.
Preferably, the top, or web-facing layer of the triple layer belt,
has a finer mesh than the bottom, or machine-facing layer. The
finer mesh provides a better fiber support and minimizes the amount
of pinholes. The bottom layer utilizes coarser yarns to increase
rigidity and improve seam strength. In a triple layer belt, the tie
yarns may be specifically added to perform the function of linking
the two independent layers together, without being present in
either layer as a part of its inherent structure. Alternatively,
the tie yarns may be the integral yarns forming the top and/or
bottom layers of the reinforcing structure. In both cases, the tie
yarns may be oriented in either the machine direction or the cross
machine direction. Machine direction tie yarns are preferred
because of the increased seam strength they provide.
European patent WO 91/14813 issued to Wright on Oct. 3, 1991 and
assigned to Asten Group, Inc., describes a two-ply forming fabric
having an upper paper carrying layer comprising twice as many
cross-machine direction yarns as the lower, machine side, layer. A
system of machine direction yarns interweaves in a selected pattern
such that a zigzag effect is produced on the underside of the
fabric to provide improved drainage.
U.S. Pat. No. 5,454,405 issued to Hawes on Oct. 3, 1995 and
assigned to Albany International Corp. describes a triple-layer
papermaking fabric having a system of top weft yarns and a system
of bottom weft yarns interwoven with paired first and second warp
yarns. The second warp yarns have relatively little crimp which
increases stretch resistance in the fabric.
Although the use of double layer and triple layer reinforcing
structures helps to balance the trade-off between the fiber support
and the air permeability of the belt, the use of double and triple
layer structures cannot, by itself, decouple these inherently
interconnected characteristics.
Accordingly, it is an object of the present invention to provide an
improved papermaking belt which substantially reduces the negative
consequences of the trade-off between the air permeability and the
fiber support of the belt. It is a purpose of the present invention
to increase the available air permeability of the belt at constant
fiber support, or to increase the available fiber support of the
belt at constant air permeability.
SUMMARY OF THE INVENTION
A papermaking fabric of the present invention is comprised of three
primary elements: a top layer of interwoven top layer yarns, a
bottom layer of interwoven bottom layer yarns, and a plurality of
tie yarns. In its preferred embodiment, the papermaking fabric is a
flat-woven endless belt which has a web-facing side and a
machine-facing side opposite the web-facing side.
The papermaking fabric of the present invention may also have a
resinous framework joined to the papermaking fabric and extending
outwardly from the web-facing side of the top layer to form a
web-contacting surface of the papermaking fabric.
The top layer yarns comprise a plurality of top layer carrier yarns
interwoven in a weave with a plurality of top layer cross-carrier
yarns. The top layer carrier yarns are substantially perpendicular
to the top layer cross-carrier yarns. Preferably, the plurality of
top layer carrier yarns are oriented in the machine direction.
Alternatively, the plurality of top layer carrier yarns may be
oriented in the cross-machine direction.
The bottom layer yarns comprise a plurality of bottom layer carrier
yarns interwoven in a weave with a plurality of bottom layer
cross-carrier yarns. The bottom layer carrier yarns are
substantially perpendicular to the bottom layer cross-carrier
yarns. Preferably, the plurality of bottom layer carrier yarns are
oriented in the machine direction.
The top layer and the bottom layers are tied together in a
substantially parallel and interfacing relationship by a plurality
of tie yarns having the same general direction as the plurality of
top layer carrier yarns. The tie yarns may comprise adjunct tie
yarns. Adjunct tie yarns are not inherent in the weave of either
the top layer or the bottom layer and are used only for the
purposes of joining the top layer and the bottom layer.
Alternatively, the tie yarns may comprise integral tie yarns. The
integral tie yarns are in the weave of the top layer and/or the
bottom layer. The integral tie yarns may be top-integral tie yarns,
bottom-integral tie yarns, or top/bottom-integral tie yarns. The
tie yarns pass over the top layer cross-carrier yarns and under the
bottom layer cross-carrier yarns in a repeating pattern such that
each of the plurality of tie yarns passes at spaced intervals over
at least one of the top layer cross-carrier yarns and under at
least one of the bottom layer cross-carrier yarns.
As the tie yarns pass over the top layer cross-carrier yarns and
under the bottom layer cross-carrier yarns, each of the tie yarns
bilaterally alternates about at least one of the top layer carrier
yarns and/or at least one of the bottom layer carrier yarns. Each
of the tie yarns alternates in the direction of the top layer
cross-carrier yarns. As a result of this bilateral alternation,
each of the tie yarns forms an undulating line passing completely
underneath at least one of the top layer carrier yarns, about which
this tie yarns alternates, at spaced intervals intermediate two
adjacent maxima of bilateral alternation of each of the tie
yarns.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary top plan view of a papermaking fabric
according to the claimed invention, having adjunct tie yarns and a
framework, and shown partially in cutaway for clarity. The bottom
layer is not shown for clarity.
FIG. 1A is a top plan view of a papermaking fabric, similar to FIG.
1, but having a more homogeneous distribution of maxima of
bilateral alternation than the papermaking fabric illustrated in
FIG. 1.
FIG. 2 is a vertical cross-sectional view taken along line 2--2 of
FIG. 1, showing an element of the framework and the adjunct tie
yarns forming undulating lines passing completely underneath the
top layer carrier yarns and the bottom layer carrier yarns.
FIG. 3 is a vertical cross-sectional view taken along line 3--3 of
FIG. 1.
FIGS. 2-3 show the resinous framework in phantom.
FIG. 4 is a vertical cross-sectional view of the papermaking fabric
according to the claimed invention, showing the adjunct tie yarns
forming undulating lines passing completely underneath only the top
layer carrier yarns.
FIG. 5 is a vertical cross-sectional view of the papermaking fabric
according to the claimed invention, having fewer bottom layer
carrier yarns than top layer carrier yarns.
FIG. 6 is a vertical cross-sectional view of the papermaking fabric
according to the claimed invention, showing the bottom-integral tie
yarns.
FIG. 7 is a vertical cross-sectional view perpendicular to the view
shown in FIG. 2, showing the adjunct tie yarns forming undulating
lines passing completely underneath the top layer carrier yarns and
the bottom layer carrier yarns.
FIG. 8 is a vertical cross-sectional view similar to the view shown
in FIG. 3, showing a bottom-integral tie yarns passing completely
underneath a top layer carrier yarn and forming a
"one-over/seven-under" repeating pattern of the tie layers
interwoven with the top layer.
FIG. 9 is a vertical cross-sectional view similar to the view shown
in FIG. 8 and showing another embodiment of the bottom-integral tie
yarn.
FIG. 10 is a vertical cross-sectional view similar to the view
shown in FIG. 8, showing another embodiment of the bottom-integral
tie yarn forming a "one-over/five-under" repeating pattern of the
tie layers interwoven with the top layer.
FIG. 11 is a vertical cross-sectional view similar to the view
shown in FIG. 10, showing still another embodiment of the
bottom-integral tie yarn forming a "one-over/three-under" repeating
pattern of the tie layers interwoven with the top layer.
FIG. 12A is a schematic cross-sectional view of the papermaking
fabric having top/bottom-integral tie yarns.
FIG. 12B is a view similar to FIG. 12A showing another embodiment
of the papermaking fabric having top/bottom-integral tie yarns.
FIG. 13 is a plan view of the papermaking papermaking fabric of the
prior art, showing non-alternating tie yarns.
FIG. 14 is a vertical cross sectional view similar to that shown in
FIG. 9, and showing a complete repeating pattern of bilateral
alternation of a tie yarn.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1-11, the papermaking fabric 10 of the present
invention preferably comprises a flat-woven endless belt which
carries a web of cellulosic fibers from a forming wire to a drying
apparatus, typically a heated drum, such as a Yankee drying drum
(not shown). Although the preferred embodiment of the papermaking
fabric 10 is in the form of an endless belt, it can be incorporated
into numerous other forms which include, for instance, statutory
plates for use in making handsheets or rotating drums for use with
other types of continuous or batch processes. As used hereinafter,
the term "papermaking belt" (or simply "belt") is synonymous to the
term "papermaking fabric" (or simply, "fabric").
The papermaking belt 10 of the present invention comprises three
primary elements: a top layer 12 of interwoven top layer yarns 100,
a bottom layer 20 of interwoven bottom layer yarns 200, a plurality
of tie yarns 300. The top layer 12 is a web facing layer, and the
bottom layer 20 is a machine facing layer of the belt 10. As will
be discussed in greater detail below, the terms and numeric
references "top layer yarns 100," "bottom layer yarns 200," "tie
yarns 300" are generic terms and numeric references which include
and designate different types of top layer yarns, bottom layer
yarns, tie yarns, respectively.
Referring now to FIGS. 1-3, the top layer 12 has a web facing side
14, and the bottom layer 20 has a machine facing side 24. The belt
10 may comprise a framework 40 joined to the belt 10 and extending
outwardly from the web facing side 14 of the top layer 12 to form a
web-contacting surface 44. Preferably, the framework 40 is cast
from a photosensitive resin onto the top layer 12.
When made from a photosensitive resin, the framework 40 penetrates
the structure of the belt 10 and is cured into any desired pattern
by irradiating liquid resin with actinic radiation through a binary
mask having opaque sections and transparent sections. A variety of
suitable resins can be used as the framework 40. The aforementioned
U.S. Pat. No. 4,529,480; U.S. Pat. No. 4,514,345; U.S. Pat. No.
4,528,349, U.S. Pat. No. 5,334,289, describing the framework 40 in
greater detail, are incorporated herein by reference.
The top layer yarns 100 of the papermaking belt 10 are comprised of
a plurality of top layer carrier yarns 110 interwoven in a weave
with a plurality of top layer cross-carrier yarns 120. The top
layer carrier yarns 110 are substantially perpendicular to the top
layer cross-carrier yarns 120. FIG. 1 shows a preferred
one-over/one-under square weave of the top layer yarns 100, but it
is to be recognized that other weaves may be utilized. The examples
of the suitable weave patterns include, but are not limited to full
twill, broken twill, semi-twill, and multi-shed satins.
Similarly to the top layer yarns 100, the bottom layer yarns 200
are comprised of a plurality of bottom layer carrier yarns 210
interwoven in a weave with a plurality of bottom layer
cross-carrier yarns 220, the bottom layer carrier yarns 210 being
substantially perpendicular to the bottom layer cross-carrier yarns
220. Preferably, but not necessarily, the bottom layer 20 has a
square weave, in order to maximize seam strength. As used herein,
top layer yarn 100 is generic to and inclusive of the top layer
carrier yarns 110 and the top layer cross-carrier yarns 120.
Analogously, bottom layer yarn 200 is generic to and inclusive of
the bottom layer carrier yarns 210 and the bottom layer
cross-carrier yarns 220.
It is preferred that the top layer carrier yarns 110 and the bottom
layer carrier yarns 210 have a machine direction. Alternatively,
the top layer carrier yarns 110 and the bottom layer carrier yarns
210 may have a cross-machine direction. As one skilled in the art
will recognize, the term "machine direction" refers to that
direction which is parallel to the principal flow of the paper web
through the papermaking apparatus. The "cross-machine direction" is
perpendicular to the machine direction and lies within the plane of
the belt 10. The machine direction of the carrier yarns 110, 210 is
preferred to maximize seam strength of the belt 10. However,
arrangements having the carrier yarns 110, 210 disposed in the
cross-machine direction may also be utilized.
As shown in FIGS. 2-11, the top layer 12 and the bottom layer 20
are tied together in a substantially parallel and interfacing
relationship by the plurality of tie yarns 300. Preferably, the top
layer 12 and the bottom layer 20 are tied together in an abutting
relationship. If desired, as FIG. 2 shows, each top layer carrier
yarn 110 is stacked in a vertical alignment with one bottom layer
carrier yarn 210; and as FIG. 3 shows, each top layer cross-carrier
yarn 120 is stacked in a vertical alignment with one bottom layer
cross-carrier yarn 220. Although the embodiment having a vertical
alignment is preferred, it is not necessary. For example, only the
carrier yarns 110, 210 may be stacked in a vertical alignment,
while the cross-carrier yarns 120, 220 are not, or vice versa.
Also, the top layer 12 and the bottom layer 20 my be slightly
displaced relative each other from the vertical alignment in the
direction of carrier yarns 110, 210, or in the direction of
cross-carrier yarns 120, 220. The top layer 12 may have the top
layer yarns 100 which are spaced more closely than the bottom layer
yarns 200 are--to provide a sufficient fiber support. FIG. 9
represents the embodiment in which every second top layer
cross-carrier yarn 120 has and is stacked in a vertical alignment
with one bottom layer cross-carrier yarn 220.
As best seen in FIGS. 1 and 1A, the tie yarns 300 have the same
general direction as the top layer carrier yarns 110. It will be
noted that, for the purposes of illustration, the tie yarns 300
have been shaded in FIGS. 1-11 and 13. As FIG. 1 shows, the tie
yarns 300 pass over some of the top layer cross-carrier yarns 120
in a repeating pattern. The repeating pattern is formed by the
plurality of tie yarns 300 as each tie yarn 300 passes at spaced
intervals over at least one of the top layer cross-carrier yarns
120 and under at least one of the bottom layer cross-carrier yarns
220. (The bottom layer cross-carrier yarns are not shown in FIG. 1
for clarity.) With regard to the top layer 12, the spaced interval
shown in FIGS. 1 and 1A includes eight top layer cross-carrier
yarns 120. In other words, inasmuch as the individual tie yarn 300
is concerned, the repeating pattern shown in FIGS. 1 and 1A is
formed by each individual tie yarn 300 passing over one top layer
cross-carrier yarn 120, then passing under seven top layer
cross-carrier yarns 120, then passing over one top layer
cross-carrier yarn 120, then again passing under seven top layer
cross-carrier yarns 120, and so on (i.e., a "one-over/seven-under"
pattern). As best seen in FIG. 3, when the tie yarn 300 passes
under seven top layer cross-carrier yarns 120, the tie yarn 300
also passes under at least one of the bottom layer cross-carrier
yarns 220, thereby joining the top layer 12 and the bottom layer 20
together.
One of ordinary skill in the art will recognize that the
"one-over/seven-under" pattern of the weave of the tie yarns 300
with the top layer 12 is one preferred, but not necessary,
embodiment of the belt 10 of the present invention. For example,
FIG. 10 shows a "one-over/five-under" pattern; and FIG. 11 shows a
"one-over/three-under" pattern of the weave of the tie yarns 300
with the top layer 12. The examples shown in FIGS. 1-12 are
presented for the purposes of illustration only, and not for the
purposes of limitation.
As has been noted above, the preferred embodiment of the belt 10 is
in the form of an endless belt. Therefore, it should be recognized
that, as used herein, the terms "over," "above," "under,"
"underneath" are relative terms, the descriptive meanings of which
are consistent with the descriptive meanings of the terms "top
layer 12" and "bottom layer 20" of the belt 10 as it is shown in
cross-sectional views represented in FIGS. 2-11 and used in its
normal and ordinary position on a papermaking machine.
Referring back to FIG. 1, as each tie yarn 300 passes, or weaves,
over at least one of the top layer cross-carrier yarns 120, each
tie yarn 300 bilaterally alternates about at least one of the top
layer carrier yarns 110. As FIG. 1 shows, each tie yarn 300
bilaterally alternates about one corresponding top layer carrier
yarn 110 in the direction of the top layer cross-carrier yarns 120.
In the preferred embodiment, at the point where the tie yarn 300
passes over the top layer cross-carrier yarn 120, the tie yarn 300
reaches its maximum of bilateral alternation. As used herein, the
term "maximum of bilateral alternation" refers to the greatest
deviation of the tie yarn 300 from the longitudinal axis of the
corresponding carrier yarn 110, as measured in the plane of the
belt 10. A "corresponding" carrier yarn (or simply, a corresponding
yarn) is the carrier yarn about which the tie yarn 300 alternates
in the plane of the belt 10. It should be carefully noted that the
corresponding yarn may be an inherent element of the weave of the
top layer 12, the bottom layer 20, or both--the top layer 12 and
the bottom layer 20. As a result of the bilateral alternation, each
tie yarn 300 forms an undulating line passing completely underneath
the top layer carrier yarn 110 at spaced intervals intermediate two
adjacent maxima of bilateral alternation of this tie yarn 300. It
should be noted that when the tie yarns 300 pass over the top layer
cross-carrier yarns 120, the tie yarns 300 preferably do not extend
above the top layer carrier yarns 110, and therefore do not
interfere with the preferred flat-woven character of the web facing
side 14 of the belt 10.
FIGS. 1 and 1A show two different overall patterns of distribution
of the maxima of bilateral alternation of the tie yarns 300. FIG. 1
represents an overall pattern having concentrated zones of the
maxima of bilateral alternation (running "diagonally" relative to
the machine direction in FIG. 1). FIG. 1A shows an overall pattern
having the maxima of bilateral alternation which is less
concentrated than the pattern shown in FIG. 1. The overall pattern
of FIG. 1A is preferred, because it provides a more even and
homogeneous distribution of occluded areas created at and around
the points of the maxima of bilateral alternation of tie yarns
300.
The overall pattern shown in FIG. 1A is represented for the
purposes of illustration and not for the purposes of limitation.
One skilled in the art will readily understand that other overall
patterns of distribution of the maxima of bilateral alternation of
the tie yarns 300, providing an even distribution of the maxima of
bilateral alternation of tie yarns 300 throughout the belt 11 may
be utilized. For example, a non-uniform overall pattern (not shown)
may be utilized, in which the maxima of bilateral alternation are
distributed in a non-repeating, or even disorderly, manner.
Preferably, every tie yarn 300 is in direct contact with its
corresponding carrier yarn 110 at the point where the tie yarn 300
reaches its maximum of bilateral alternation. Therefore, the
corresponding carrier yarns 110 do not let the tie yarns 300 to
stretch into a completely straight line and to become parallel to
the carrier yarns 110 between two adjacent maxima of bilateral
alternation even if the tie yarns 300 are pre-stretched in the
machine direction. The specific weave of the belt 10 of the present
invention results in the tie yarns 300 forming the undulating
lines. Therefore, there is no need in a special pre-treatment of
the tie yarns 300 (for example, chemical treatment or
thermosetting) for the purposes of making the tie yarns 300 form
the undulating lines.
While the tie yarns 300 are preferably never parallel to their
corresponding top layer carrier yarns 110 between two adjacent
maxima of bilateral alternation, it should be carefully noted that
the tie yarns 300 have the same general direction as the top layer
carrier yarns 110, as has been indicated hereabove and shown in
FIG. 1. As used herein, the term "general direction" designates a
direction of the tie yarns 300 that occurs throughout a series of
at least four consecutive maxima of bilateral alternation.
With regard to the bottom layer 20, FIGS. 3, 7, 8, 9, 10, 11
represent different embodiments of the belt 10 of the present
invention. First, it should be noted that the tie yarns 300 may
comprise adjunct tie yarns 330. Alternatively, the tie yarns 300
may comprise integral tie yarns 350. As used herein, the tie yarn
300 is considered to be an "adjunct tie yarn" 330 if it is not
inherent in the weave selected for either one of the top layer 12
or the bottom layer 20. That is to say, the top layer 12 and the
bottom layer 20 exist as independent structures of interwoven top
layer yarns 100 and the interwoven bottom layer yarns 200
respectively, regardless of the existence of the adjunct tie yarns
330. The adjunct tie yarns 330 are used only for the purpose of
joining the top layer 12 and the bottom layer 20 together and may
even disrupt the ordinary weave of these top and bottom layers 12,
20. Preferably, the adjunct tie yarns 330 are smaller in
cross-sectional area than the top layer yarns 100 and the bottom
layer yarns 200.
As used herein, the tie yarn 300 is considered to be an "integral
tie yarn" 350 if it is an inherent element of the weave of the top
layer 12, the bottom layer 20, or both the top layer 12 and the
bottom layer 20. The integral tie yarn 350 is a "bottom-integral
tie yarn" if it is an inherent element of the weave of the bottom
layer 20 and only occasionally passes over the top cross-carrier
yarn 120. The integral tie yarn 300 is a "top-integral tie yarn" if
it is an inherent element of the weave of the top layer 12 and
occasionally passes under the bottom cross-carrier yarn 220. FIGS.
8, 9 show two embodiments of the belt 10 of the present invention
having the preferred bottom-integral tie yarns 352. In both
embodiments shown in FIGS. 8 and 9, the bottom layer 20 is
comprised of the bottom-integral tie yarns 350 which are interwoven
with the bottom layer cross-carrier yarns 220. In both embodiments
shown in FIGS. 8 and 9, the bottom-integral tie yarns 350 function
also as (and in fact are) the bottom layer carrier yarns 210.
It will be apparent to one skilled in the art that in the belt 10
having the top-integral tie yarns 350, the top layer 12 is
comprised of the top-integral tie yarns 350 interwoven with the top
layer cross-carrier yarns 120. In this case, the top-integral tie
yarns 350 also function as the top layer carrier yarns 120. The
latter embodiment is not illustrated, but may be easily envisioned
by turning FIGS. 8, 9 upside down. In this case, as each top
integral tie yarn 350 passes under or over at least one of the
bottom layer cross-carrier yarns 220, each top-integrated tie yarn
350 bilaterally alternates about at least one of the bottom layer
carrier yarns 210. As a result of this bilateral alternation, each
top-integral tie yarn 350 forms an undulating line passing
completely over or underneath the bottom layer carrier yarn 110 at
spaced intervals intermediate two adjacent maxima of bilateral
alternation of the top-integral tie yarn 350.
One skilled in the art will recognize that a variety of possible
patterns of the tie yarns 300 interwoven with the top layer 12 and
the bottom layer 20 of the belt 10 may be utilized. Some of these
patterns are shown in FIGS. 3, 7, 8, 9, 10, 11. FIGS. 3, 7
represent the belt 10 having the adjunct tie yarns 330, while FIGS.
8-11 represent the belt 10 having the integral tie yarns 350. FIG.
3 shows the typical embodiment of the belt 10 comprising the
adjunct tie yarns 330. In the belt 10 shown in FIG. 3, the adjunct
tie yarn 330 is interwoven with the top layer 12 according to the
pattern "one-over/seven-under" described hereabove. The adjunct tie
yarn 330 is interwoven with the bottom layer 20 according to the
similar pattern "seven-over/one-under." The bottom layer
cross-carrier yarn 220 under which the adjunct tie yarn 330 passes
while running under seven top layer cross-carrier yarns 120, is
disposed intermediate two adjacent top layer cross-carrier yarns
120 over which the adjunct tie layer 330 passes. As FIG. 3 shows,
most of the length of the adjunct tie yarn 330 is disposed between
the top layer 12 and the bottom layer 20.
Other embodiments of the belt 10 of the present invention are
feasible, given the various combinations of the top/bottom layer
vs. adjunct/ integrated tie yarns and permutations of the foregoing
teachings. The described combinations are not intended to limit the
present invention to only those that are described and shown
above.
For example, FIGS. 12A and. 12B schematically illustrate two
embodiments of the belt 10 in which the tie yarn 300 comprises a
top/bottom-integral tie yarn 390. As the term suggests, the
top/bottom-integral tie yarn 390 is an inherent element of the
weave of both the top layer 12 and the bottom layer 20. In this
case, the plurality of top layer carrier yarns 110 and the
plurality of bottom layer carrier yarns comprise a plurality of the
top/bottom-integral tie yarns 390. When the carrier yarns 110, 210
are oriented in the machine direction, the top/bottom-integral tie
yarns 390 are the machine direction top/bottom-integral tie yarns
390, as shown in FIGS. 12A and 12B. By analogy, when the carrier
yarns 110, 210 are oriented in the cross-machine direction, the
top/bottom integral tie yarns 390 are the cross-machine direction
top/bottom-integral tie yarns 390 (not shown).
As FIGS. 12A and 12B show the top layer 12 and the bottom layer 20
are tied together in a substantially parallel and interfacing
relationship by the machine direction top/bottom-integral tie yarns
390. These machine direction top/bottom-integral tie yarns 390 pass
over some of the cross-machine direction top layer yarns 120 and
under some of the cross-machine direction bottom layer yarns 220 in
a repeating pattern and at spaced intervals such that as each of
the machine direction top/bottom-integral tie yarns 390 passes over
at least one of the cross-machine direction top layer yarns 120 and
under at least one of the cross-machine direction bottom layer
yarns 220, each of the machine direction top/bottom-integral tie
yarns 390 bilaterally alternates in the cross-machine direction
about at least one (corresponding) machine direction top layer yarn
110 and about at least one (corresponding) machine direction bottom
layer yarn 210. (Yarns 110 and 120 are not shown in FIGS. 12A and
12B for clarity.) As a result of this bilateral alternation, each
of the machine direction top/bottom-integral tie yarns 390 forms an
undulating line having a general machine direction and passing
completely underneath the corresponding machine direction top layer
yarn 110 and completely over the corresponding machine direction
bottom layer yarn 210 at spaced intervals intermediate two adjacent
maxima of bilateral alternation of each of the machine direction
tie/bottom-integral tie yarns 390.
It is important, especially in the case of through-air-drying, that
the belt 10 of the present invention allow sufficient air flow
perpendicular to the plane of the belt 10. Preferably, the air
permeability of the belt 10 (having no resinous framework 40
thereupon) of the present invention is greater than 500 standard
cubic feet per minute (cfm) per square foot of its surface at a
pressure differential of 100 Pascals. More preferably, the belt 10
(having no resinous framework 40 thereupon) has the air
permeability greater than 800 cfm at 100 Pascals.
While not intended to be bound by theory, it is believed that the
belt 10 of the present invention having bilaterally alternating tie
yarns provides the increased air permeability compared with the
similar belt having non-alternating tie yarns. FIG. 13 illustrates
the prior art and shows the belt 700 having non-alternating tie
yarns 800. As FIG. 13 shows, the non-alternating tie yarns 800 of
the prior art substantially reduce the belt's projected open areas
between the mutually perpendicular interwoven yarns 100, 200. In
the present invention, the tie yarns 300, by virtue of their
bilateral alternation, minimize reduction of the open area of the
belt 10 and therefore minimize interference with the air flow
through the belt 10.
Two two-layer belts--first, the belt 10 of the present invention,
having the alternating tie yarns, and the second, the belt 700 of
the prior art, having non-alternating tie yarns--are being
compared. Both belts 10 and 700 have the following
characteristics:
the diameter of the top layer carrier yarns is 0.15 mm,
the number of the top layer carrier yarns is 45 yarns per inch,
the diameter of the top layer cross-carrier yarns is 0.15 mm,
the number of the top layer cross-carrier yarns is 48 yarns per
inch;
the diameter of the bottom layer carrier yarns (bottom-integral tie
yarns) is 0.15 mm;
the number of the bottom layer carrier yarns (bottom-integral tie
yarns) is 45 yarns per inch,
the diameter of the bottom layer cross-carrier yarns is 0.20
mm,
the number of the bottom layer cross-carrier yarns is 24 yarns per
inch.
Both belts 10 and 700 have the one-over/one-under inherent weave of
the top and bottom layers and the "one-over/seven-under" weave of
the bottom-integral tie yarns described hereabove. Both belts 10
and 700 have the similar overall pattern of locations where the tie
yarns pass over the top layer cross-carrier yarns, as shown in
FIGS. 1 and 13, respectively (in the case of the belt 10 of the
present invention, these locations comprise maxima of bilateral
alternation of the tie yarns).
Presumptively, because of the use of the identical fibers and the
weave patterns in both belts, both belts have about the same fiber
support. It is believed that the use of the alternating tie yarns
in the first belt 10 made according to the present invention
increases the projected open area at least about 15%, compared to
the projected open area of the second belt 700 having the
non-alternating tie yarns of the prior art.
At the same time, the use of alternating tie yarns 300 according to
the present invention provides the necessary fiber support. As used
herein, the "fiber support," and especially, its physical
characteristic "Fiber Support Index," is defined in Robert L.
Beran, "The Evaluation and Selection of Forming Fabrics," Tappi
/April 1979, Vol. 62, No. 4, which is incorporated by reference
herein. As has been shown hereabove, a trade-off exists between the
air permeability and the fiber support of the papermaking belt.
Therefore, if the belts 10 and 700 are prophetically rewoven to be
compared on the basis of the same air permeability (or the same
projected open area), the use of the alternating yarns in the belt
10 of the present invention increases the Fiber Support Index more
than about 20%, compared to the belt 700 of the prior art having
about the same projected open area but non-alternating tie
yarns.
The yarns 100, 200, 300 may have a variety of cross-sectional
shapes, including but not limited to circles, ovals, rectangles,
and other polygons. For example, the top layer yarns 100 and the
bottom layer yarns 200 may have cross-sectional areas shaped as
circles of equal or unequal diameters, while the tie yarns 300 may
be flat. In any case, the cross-sectional area of the bottom yarns
200 may be greater than the cross-sectional area of the top yarns
100. It follows, the cross-sectional area of the top yarns 100 may
be greater than the cross-sectional area of the tie yarns 300.
Generally, the yarns 100, 200, 300 of the papermaking belt of the
present invention may be produced from a wide specter of synthetic
resins. When used in a through-air-drying belt, the preferred
material of the yarns 100, 200, 300 of the belt 10 is Poly
(ethylene terephthalate).
While the present invention has been discussed and the FIGS. 1-12
have been presented in terms of monofilament yarns, one skilled in
the art will recognize that the yarns 100, 200, 300 may comprise
multifilament yarns and plied monofilament yarns.
The papermaking fabric of the present invention can be made using a
conventional weaving technique and conventional weaving equipment.
Alteratively, the papermaking fabric can be made by hand.
FIG. 14 is used herein as a reference to describe a step-by-step
process of weaving by hand of the papermaking fabric. In an
exemplary pattern shown in FIG. 14, MD yarns are designated by the
numerals 110 and 350, and CD yarns are designated by the generic
numerals 120 and 220. For the convenience of describing the process
of weaving, the individual top-layer CD yarns are designated as
120a, 120a, 120c, . . . , and so on, in alphabetic order; and the
individual bottom-layer CD: yarns are designated as 220a, 220b,
220c, . . . , and so on, in alphabetic order. In FIG. 14, the tie
yarns comprise the MD bottom-layer integral tie yarns 350.
First, a plurality of MD yarns and CD yarns is provided. The MD
yarns are placed in the machine direction. Then, the weaving
process comprises the following steps (described here in below in
the form of the instructions, with reference to FIG. 14). For
convenience, the description of the process starts just prior to
the point when the tie yarn 360 reaches its maximum of bilateral
alternation, which point is adjacent to the yarn 120a (at the
left-hand side of FIG. 14).
(1) Raise MD yarn 110 and raise MD tie yarn 350. Place CD yarn 120a
below tie yarn 350 and below yarn 110.
(2) Lower MD tie yarn 350, and lower MD yarn 110. Place CD yarn
120b above tie yarn 350 and above yarn 110.
(3) Raise MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220a below tie yarn 350 and below yarn 110.
(4) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
120c above tie yarn 350 and below yarn 110.
(5) Lower MD tie yarn 350, and lower MD yarn 110. Place CD yarn
120d above tie yarn 350 and above yarn 110.
(6) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220b above tie yarn 350 and below yarn 110.
(7) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
120e above tie yarn 350 and below yarn 110.
(8) Lower MD tie yarn 350, and lower MD yarn 110. Place CD yarn
12Of above tie yarn 350 and above yarn 110.
(9) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220c above tie yarn 350 and below yarn 110.
(10) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
120g above tie yarn 350 nd below yarn 110.
(11) Lower MD tie yarn 350, and lower MD yarn 111. Place CD yarn
120h above tie yarn 350 and above yarn 11.
(12) Raise MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220d below tie yarn 350 and below yarn 110.
(13) Switch MD tie yarn 350 and MD yarn 110 in plan, i.e.,
"alternate" MD tie yarn 350 about MD yarn 110 in the cross-machine
direction.
(14) Raise MD tie yarn 350, and raise MD yarn 110. Place CD yarn
120i below tie yarn 350 and below yarn 110. (At this point, tie
yarn 350 reaches its maximum of bilateral alternation.)
(15) Lower MD tie yarn 350, and lower MD yarn 10. Place CD yarn
120j above tie yarn 350 and above yarn 110.
(16) Raise MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220e below tie yarn 35 and below yarn 110.
(17) Lower MD tie yarn 350, and raise MD yarn 11O. Place CD yarn
120k above tie yarn 35 and below yarn 110.
(18) Lower MD tie yarn 350, and lower MD yarn 110. Place CD yarn
1201 above tie yarn 360 and above yarn 110.
(19) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220f above tie yarn 350 and below yarn 110.
(20) Lower MD tie yarn 350, and raise MD yarn 110. Place CD yarn
120m above tie yarn 350 and below yarn 110.
(21) Lower MD tie yarn 350, and lower MD yarn 110. Place CD yarn
120n above tie yarn 350 and above arn 11O.
(22) Lower MD tie yarn 350, and raise yarn 110. Place CD yarn 220g
above tie yarn 350 and below yarn 110.
(23) Lower MD tie yarn 350, and raise D yarn 110. Place CD yarn
120o above tie yarn 350 and below yarn 110.
(24) Lower MD tie yarn 350, and lower MD yarn 110. Place CD yarn
120p above tie yarn 350 and above yarn 110.
(25) Raise MD tie yarn 350, and raise MD yarn 110. Place CD yarn
220h below tie yarn 350 and below yarn 110.
(26) Switch back MD tie yarn 350 and MD yarn 110 in plan, i.e.,
"alternate" MD tie yarn 350 about MD yarn 110 in the cross-machine
direction.
Thereafter, the process continues fro the step 1 ), ad described
herein above.
* * * * *